I'm entering week 8 and one of my three blue dream'atic autos is much more advanced versus the other 2 (see photos)
Buds are getting nice and sticky but in the past week, she's had some upper leaves around the main cola start getting brown spots, dried and crispy/brittle to the point where they crumble if I pinch them. The brown spots started appearing near the tip but not at the very tip, followed by general yellowing in the leaf area.
To try and solve, I did the following:
Flushed and fed again, adding cal mag because I suspected a possible deficiency
Moved lights away to ~14 inches
The yellow/crispiness is getting worse now and some other colas are showing some signs. I will also mention that before this started, the plant started showing some curling up of the serrated leaf edges. All the lower leaves are moist and healthy looking. Also this plant in general is just a bit weird, having been quite a bit more advanced than the other two (despite same chornological age) and with buds that wide and blunt without the pointy tips most buds (including the other 2 plants) form.
General grow/plant conditions:
The RH is between 45 - 52@ and temp is usually around 75-78, although it has gotten up to 81 on some days during late flower
Lights (300w LED) are always 8-14 inches away and there are other colas on plants that are taller and show no burn issues
I use FF trio nutrients and always pH my water (and added cal mag in the last feed because of suspected issue)
I have two fans, one blowing (not too violently) over the canopy and one blowing under the canopy
Trichomes on top buds are mix of clear and cloudy
No insects or obvious signs of mold/mildew/bud rot
Autos tend to yellow in late flower but i would check your ph, if high white vinegar will lower if low bakeing soda will raise, allso autos need about a 1/4 of nutes needed by photoperid plants. This auto had a high ph so lowerd back down at 10 weeks needs more time although the pistols are turning a nice yellow, toofless alien an f2 strain.
I ran dozens of blue dream photos on coco…….I saw cal mag issues that looked exactly like yours do untill I bumped them up to 350ppm cal mag on top of my 4PPM ro water….and that was at week 6 flower… Blue dream is a known cal mag hog…, but it’s also ridiculously resilient I brought mine back from the brink of death I almost chopped them all down it was embarrassing I’m glad I didn’t because it was my largest harvest today one of the plants 21 1/2 sips by itself after the jar and that one was fucked up the most
What is your PAR/PPFD? Any kind of light quantity measurement at all? It looks to me like you've scorched your plants and mostly killed leaves with light burn. My first grow with autos looked very similar.